- A QR code is just a picture that contains text, usually a web address.
- Check the address on screen before opening it, especially for payments and logins.
- Be cautious with codes stuck over other codes or sent by strangers.
The short answer
A QR code, short for Quick Response code, is a square pattern of black and white modules that stores information such as a web address, a phone number or Wi-Fi details. Your phone camera reads the pattern and shows you the content. They are convenient for menus, tickets, payments and event pages, but because you cannot read a code with your eyes, they can also hide a bad link.
Where QR codes came from
QR codes were invented in 1994 by Denso Wave, a Japanese company, to track car parts in factories. They could store more data than the older barcode and be read quickly from any angle. The company let others use the technology freely, which helped it spread across the world.
How they work
The pattern holds the data in a grid. Three large squares in the corners tell the camera where the code is and how it is rotated. The rest of the grid holds the information plus extra error-correction data, so a code can still be read when part of it is dirty or covered. There are four correction levels, with the highest able to recover roughly 30 percent of damaged data.
Static and dynamic codes
| Type | What it means |
|---|---|
| Static | The information is fixed inside the code and cannot be changed after printing. |
| Dynamic | The code points to a short link that can be redirected later and often tracks scans. |
Businesses use dynamic codes so they can update a menu or offer without reprinting. That flexibility is also why you should check where a code really sends you.
Everyday uses
- Restaurant menus, event tickets and boarding passes.
- Sharing a Wi-Fi password with guests.
- Paying a business through a payment app.
- Linking posters and flyers to a song, a video or a booking page.
- Adding a contact to a phone.
How scammers misuse QR codes
Scammers print fake codes on stickers and place them over real ones, send codes by email or message, or use them on fake parking or payment notices. Scanning leads to a copy of a real login or payment page that steals your details. This trick is sometimes called QR phishing. It works the same way as the message tricks in our guide to phishing emails and SMS scams.
How to scan safely
- Look at the code first. If it looks like a sticker placed over another one, do not scan it.
- Scan with your normal phone camera or a trusted app, and read the web address your phone shows before you tap it.
- Check that the address matches the company you expect and starts with https.
- Do not enter passwords, card numbers or one-time codes on a page you reached from an unknown code.
- If a code asks you to install an app, go to the official app store directly instead.
- When in doubt, type the website address yourself.
Making your own QR code
- Use a trustworthy generator and always test the code on two different phones.
- Keep strong contrast, such as black on white, and leave a clear border around the code.
- Print it large enough, around 2 cm or more for close scanning and bigger for posters.
- Put a short line of text near the code that says where it leads.
Quick checklist
- Read the address before opening it
- Avoid stickers placed over other codes
- Never enter passwords after scanning an unknown code
- Use the official app store for apps
- Test your own codes before printing
Key points to remember
QR codes are safe when you treat them like any other link: check where they lead before you trust them. For more protection, set up a password manager and two-factor login.
